Di-esters of 3,3&#39;-methylenebis (4-hydroxycoumarin) and process of making them



Patented Apr. 4, 1944 m-ns'rnas or as-mnrmnnnnrsu-nrnaoxroommam) MAKINGTHEM AND PROCESS OI Mark A. Stahmann and Karl Paul Link. Madlson, Wis..assignors to Wisconsin Alumni Research Foundation, Madison, Wis, acorporation of Wisconsin No Drawing. Application April 11, 1942, SerialNo. 438,564

9 Claims.

Our present invention relates to the new diesters of3,3'-methylenebls(i-hydroxycoumarin), and to the process of making them.

As is set forth in the co-pending application Serial No. 414,688, filedOctober 11, 1941, by us Jointly with Harold A. Campbell and Charles F.Huebner, the compound 3,3-methylenebis(4-hydroxycoumarin) is ananticoagulant which is suitable for administration to man. It may beobtained from spoiled sweet clover hay, by extraction procedures setforth in that co-pending application Serial No. 414,688. It may besynthesized by causing 4-hydroxycoumarin to react with formaldehyde inboiling ethyl alcohol, as is also set forth in said co-pendingapplication Serial No. 414,688. The 4-hydroxycoumarin used in thatsynthesis may itself be synthesized from acetyl methylsalicylate, byheating the latter to 165 on an oil bath in an open beaker, introducingmetallic sodium and stirring over a period of an hour, and maintainingthe temperature between 165 and 175 during that period by suitablecooling means.

The compound 3,3'-methylenebis(4-hydroxycoumarin) exists both in theenol form indicated by that name, and in the keto form3,3'-methylenebis(2,4-diketochroman); as is indicated by the followingformula:

( EH Hi) H l1, 2 i a I I C s 3,3'-methylenebis (i-hydroxyooumarin) inwhich R represents an acyl group. (By "acyl group," as we use it here,we do not include the formyl group.) The general formula of the newcompounds may also be written as follows:

in which R. represents a monovalent hydrocarbon radical which with acarboxyl group forms an organic acid.

The reaction forming these new di-esters may be represented by thefollowing formulas, for the organic-acid anhydrides and the acidchlorides respectively:

3,3'-iiiethylenebls(4-hydroxycoumarin) i e o-o-R' E'--- --0 some I. 5 ia l m r \Q r til-ester oi 3,3'-methylenebis- (i-hydroxyoo l lln)3,3-methylenebis(i-hydroxyoonmsrin) These reactions may be carried outby either of two general methods:

'methylenebis(4-hydroxycoumarin) is dissolved in a basic organicsolvent, suitably pyridine, and desirably with a minimum volume of thesolvent for obtaining solution; and the desired acid chloride (or otheracid halide) or organic acid anhydride is slowly added, in markedexcess, with constant stirring. This marked excess over the theoretica1amount is found to increase the yields; and We have found it desirableto use from 20 to 50 molecular equivalents as such excess when theorganic acid anhydride is used, and to use about 3 to molecularequivalents as such excess when an acid halide is used. Desirably thesolution is cooled before and kept cool during the addition of the acidchloride or organic acid anhydride. After such addition has beencompleted, the mixture is allowed to stand for several hours, desirablyat room temperature or less, during which time the crystals of thediester separate. These crystals are collected, and washed with asolvent in which they are insoluble but the unreacted reagents aresoluble, suitably ethyl alcohol. The crude crystals thus obtained may berecrystallized from a suitable medium, such, for instance ascyclohexanone.

Method B.--According to Method B, the 3,3- methylenebis(4hydroxycoumarin) is mixed with an excess of the organic acid anhydride,and the mixture is heated, desirably by refluxing, for several hours,conveniently at normal pressure. The mixture is then allowed to stand atrefrigerator temperature, say about 4 C., for several hours,conveniently over night, during which time the di-ester crystallizesout. The crystals may be collected, as by filtration, and washed andrecrystallized as in Method A.

The following are examples of our method, and of our new products:

EXAMPLE 1.--3,3'-methylenebis(4-hydroxzlcoumarin) diacetate Method A.Twograms (0.006 mole) of 3,3- methylenebis(4-hydroxycoumarin) are dissolvedin a minimum volume of basic organic solvent, suitably pyridine. Whenpyridine is used, 25 ml. is sufilcient, and it is desirable to heat thepyridine to efiect more rapid solution. The solution is cooled to about10 C., and 25 g. (0.24 mole) of acetic anhydride is slowly added, withstirring, while the mixture is maintained at this temperature by acooling bath. The mixture is allowed to stand about 12 hours at about 25C., during which time crystals of the diacetate separate from thesolution. These are collected, as by filtration. and washed with asolvent in which the ester is insoluble and in which the unreactedreagents are soluble, suitably methyl or ethyl or isopropyl alcohol orwater. The yield is about 2.3 g., which is about 90%. The crud productthus obtained is recrystallized from a suitable medium, such ascyclohexanone. After such recrystallization, the 3,3 methylenebishihydroxycoumarin) diacetate obtained melts with decomposition at about250-252 0.; and analyzes for CroHrqOMOCCHa) 2 In the foregoing method wemay use acetyl chloride or acetyl bromide or acetyl fluoride or acetyliodide in place of the acetic anhydride; but if acetyl fluoride is usedit is necessary to operate at lower temperatures, and thus to do moredrastic cooling.

Method B.-Five grams (0.015 mole) of 3,3-methylcnebis(i-hydroxycoumarin) is refluxed 4 hours with 60 g. (0.6mole) of acetic anhydrlde. The mixture is then allowed to stand at about4 C. for about 12 hours, to complete crystallization of the diacetate;which is collected, as by filtration, and washed with a solvent,suitably ethyl alcohol or water, to remove acetic anhydride and aceticacid. The yield is about 5.8 g., which is about 92%. The product thusobtained, without further purification as by recrystallizatio'n, meltsat about 250-252 C., with decomposition.

Method A.This dipropionate may be prepared by theprocedure given for thediacetate under Example 1, save that an excess of propionic anhydride(about 26.7 g.) or propionyl chloride is used in place of aceticanhydride or acetyl chloride. The dipropionate is separated, andrecrystallized, in the same manner as the diacetate of Example 1. Theyield is about 2.0 g., which is about 77%. 3,3 methylenebls 4hydroxycoumarin) dipropionate melts with decomposition at about 247-248C., and analyzes for C19H1006(0CCH2CH3) 2.

Method B.--Five grams (0.015 mole) of 3,3- methylenebis4-hydroxycoumarin) is refluxed with 78 g. (0.6 mol) of propionicanhydride. The mixture is then stirred to induce crystallization of thedipropionate, and is allowed to stand at about 4 C. for about 12 hoursto complete that crystallization. The crystals are collected. as byfiltration, and washed with a suitable washing solvent, suitably ethylalcohol or water, to remove propionic anhydride and propionic acid. Theyield is about 6.0 g., which is about Without further purification theproduct is found to melt at 246-248 C., with decomposition.

EXAMPLE 3.3,3'-methylenebis(4-hydroacycoumarin) di-n-lmtyrate Thisdi-n-butyrate is prepared by either Method A or Method B, in the sameprocedure as set forth under Example 1. In Method A it is convenient touse about 5.1 g. (0.048 mole) of n-butyryl chloride for this reaction,in place of acetic anhydride. The di-n-butyrate produced is separated,and recrystallized, in the same manner as the diacetate of Example 1.The yield is about 1.9 g., or about 69%. 3,3'-methylenebis(4-hvdroxycoumarin) di-n-butyrate melts at about 227-228 C., and analyzesfor Ciel-1100s (OCCHzCHzCHa) 2 Exmu 4 .3,3'-meth1!lenebis(4-hydrozucoumarin) di-iso-butw'ate 1 Eel-0 (9) 0 I Exuru:5.3,3'-methylenebis(4-hydroxycoumarin) di-n-valerate This di-n-valerateis prepared by either Method A or Method B, by procedures substantiallythe same as that for the diacetate in Example 1; in Method A about 2.9g. (0.024 mole) of nvaleryl chloride is used in place of the aceticanhydride. The di-n-valerate is separated and recrystallized in the samemanner as the diacetate. The yield is about 2.0 g., which is about 48%.3,3'-methylenebis(4 hydroxycoumarin) di-n-valerate melts at about224-225 C., and analyzes for CinHmOMOCCHzCHzCHzCI-Iah.

EXAMPLE 6.3,3'-methylenebis(4-hydromycoumarin) di-iso-valerate Thedi-iso-valerate may be prepared by either Method A or Method B, by theprocedure given for the diacetate in Example 1; thus in Method A about2.0 g. (0.024 mole) of iso-valeryl chloride is used in place of theacetic anhydride. The diiso-valerate is separated and recrystallized inthe same manner as the diacetate. The yield is about 2.2 g., which isabout 51%. 3,3'-methylenebis- (4-hydroxycoumarin) di-iso-valerate meltsat about 234-236 (1., and analyzes for camoouoccmcmcmim Exmru:7.3,3'-methylenebis(4-h1idr0x1 coumarin) di-iso-caproate Thisdi-n-caproate is prepared by either Method A or Method B, by theprocedure given for the diacetate in Example 1; thus in Method A about2.4 g. (0.018 mole) of n-caproyl chloride is used in place of the aceticanhydride. The din-caproate is separated and recrystallized in'the samemanner as the diacetate. The yield is about 1.7 g., which is about 63%.3,3'-methylenebis- (4-hydroxycoumarin) di-n-caproate melts at about220-221 C., and analyzes for- CmHmbflOCCHzCHzCHeCI-IzCHa):

EXAMPLE 8.-3,3'-meth1 lenebis(4-hudroxycoumarin) di-n-heptanoate Thisdi-n-heptanoate may be prepared by either Method A or Method B, by theprocedure given for the diacetate in Example 1; thus in Method A about3.5 g. (0.024 mole) of n-heptanoyl chloride is used in place of theacetic anhydride. The di-n-heptanoate is separated and recrystallized inthe same manner as the diacetate. The yield is about 2.3 g., which isabout 50%. 3.3 methylenebis(4 hydroxycoumarin) di-n-heptanoate melts atabout 215-216 C., and analyzes for C19H1006 OCCHzCHzCHiCHzCHzCI-Iz) 2EXAMPLE 9.--3,3'-methylenebis(4-hydr0azycoumarin) dzbenzoate Thisdibenzoate is prepared by either Method A or Method B, by the proceduregiven for the diacetate under Example 1; in Method A about 3.4 g. (0.024mole) of benzoyl chloride is used in place of the acetic anhydride. Thedibenzoate is separated and recrystallized in the same manner as thediacetate. The yield is about 2.6 g., which is about 81%.3,3'-methylenebis(4-hydroxycoumarin) dibenzoate melts with decompositionat about 263-264 C., and analyzes for CIQHIOOG (OCCsI-Is) 2 EXAMPLEl0.-3,3'-methylenebis(4-hydroxycoumarin) di-trimethylacetate Thisdi-trimethylacetate is prepared by either Method A or Method B, by theprocedure given for the diacetate in Example 1; thus in Method A about2.9 'g. (0.024 mole) of trimethylacetyl chloride is used in place of theacetic anhydride. The di-trimethylacetate is separated andrecrystallized in the same manner as the diacetate.

The yield is about 0.8 g., which is about 27%.

3,3'-methylenebis-(4-hydroxycoumarin) 'di-trimethylacetate melts'atabout 210-211 0., and analyzes for Ci9H1oOc(OCC(CH3) a) 2.

These di-esters of 3,3-methylenebis(4-hydroxycoumarin) show in .generalanticoagulant properties similar to those of the parent 3,3-methylenebis(4-hydroxycoumarin). They are most conveniently administeredorally, but may be administered ,parenterally. When administered ineither way, they act to lower the blood prothrombin level and tolengthen the clotting time of the blood, and thus act in vivo to preventclotting. Their effect is ordinarily a day or two in developing, andlasts for rather a prolonged period of time.

Itis believed that their anticoagulant action follows hydrolysis of theesters in vivo to 3,3- methylenebis(4-hydroxycoumarin) although this isnot established. That hypothesis seems probable because the esters whichare the more difiicult to hydrolyze in vitro show the less anticoagulantaction in vivo, and the esters which are most diflicult to hydrolyze,particularly the trimethylacetate, show only relatively littleantlcoagulant action. In general the higher aliphatic esters are morediflicult to hydrolyze than are the lower ones, and show lessanticoagulant action.

Thus by our esterification the anticoagulant action of a given amount of3,3'-methylenebis(4- hydroxycoumarin) is reduced, and the action isprolonged over a. greater period of time. Because of this, these estersare indicated where it is desirable to reduce the rate of action of thistype .of anti-coagulant, and to extend the period of the effect.

In consequence, :by the use of these di-esters instead of the parent3,3'-methylenebis(4-hydroxycoumarin) the likelihood of hemorrhage fromthe administration seems to be reduced; and it becomes possible toobtain anticoagulant v effects with less danger of hemorrhage. Even so,

however, excessive amounts of the esters may produce hemorrhage; and sotheir administration must be done carefully and under observation.

If overdoses are given, and a tendency to hemorrhage arises, thattendency can be combated and the prothrombin time and coagulationreturned toward or to normal by transfusions of fresh normal blood.

These di-esters, by reason of their anticoagulant action, have manyuses, both for prophylaxis and treatment, in blood-circulatory andvascular disturbances, including thrombosis, especially post-operativethrombosis, embolism, phlebitis, Buergers disease, etc. The explorationof the extent of their uses is still far from complete; but in generalthey seem to be beneficial where heparin is beneficial, and to have theadded advantages of oral administrability, prolonged action, andcomparative cheapness.

We claim as our invention:

1. The new di-esters of 3,3'-methylenebis(4- hydroxycoumarin) which havethe following general formula:

/\/ g I U iii in which R represents an acyl group.

- 2. 3,3'-methylenebis(4 hydroxycoumarin) diacetate, which has thefollowing formula:

3. The method of preparing di-esters of 3,3-methylenebis(4-hydroxycoumarin) which have the following generalformula:

in which It represents an'acyl group, which consists in reacting3,3'--methylenebis(-hydroxycoumarin) with a reagent of the classconsisting of acyl halides and organic acid anhydrides.

4. The method of preparing di-esters of 3,3-

methylenebis(4-hydroxycoumarin) as set forth in claim 3, with theaddition that the reagent is in marked excess. v 5. The method ofpreparing di-esters of 3,3-

methyienebis(4-hydroxycoumarin) as set forth in claim 3, with theaddition that the reaction is carried out in a basic organic solvent.

6. The method of preparing di-esters of 3,3'- methylenebis(l-hydroxycoumarin) as set forth in. claim 3, with the addition that thereaction is carried out in pyridine as a solvent.

7. The method of preparing di-esters of 3,3- methylenebis(l-hydroxycoumarin) which have the following general formula:

in which R represents an acyl group, which consists in treating3,3'-methylenebis(4-hydroxy coumarin) with an organic acid anhydride.

8. The method of preparing di-esters of 3,3-methylenebis(4-hydroxycoumarin) which have the following generalformula:

honedC /L in which R represents an acyl group, which consists in heating3,3-methylenebis(i-hydroxycoumarin) with an organic acid anhydride.

9. The method of preparing di-esters of 3,3-methylenebis(4-hydroxycoumarin) which have the following generalformula:

c o M /Q in which R represents an acyl group, which consists in heating3,3'-methylenebis(4-hydroxycoumarin) with an organic acid anhydrideunder reflux conditions.

- MARK A. STAHMANN.

KARL PAUL LINK.

Certificate of Correction Patent No. 2,345,635. April 4, 1944.

MARK A. STAHMANN ET AL.

It is hereby certified that errors appear in the printed specificationof the above numbered patent requiring correction as follows: Page 1,second column, line 45, in the formula, for

o o-c'i-R' read o-ti-n' and same line, for

page 3, first column, line 68, for di-iso-caproate reed di-n-caproate;and second column, line 30, for 3.3? read 3,8"; and that the saidLetters Patent should be read with these corrections therein that thesame may conform to the record of the case in the Patent Office.

Signed and sealed this 6th day of June, A. D. 1944.

[SEAL] LESLIE FRAZER,

Acting Commissioner of Patents.

